Methods for treating the thoracic region of a patient&#39;s body

ABSTRACT

A method is disclosed for the treatment of a thoracic region of a patient&#39;s body. Embodiments of the method comprise positioning an energy delivery portion of an electrosurgical device to face a segment of a thoracic vertebra at a distance from the segment; and cooling the energy delivery portion and delivering energy through the energy delivery portion.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 12/176,035 (filed Jul. 18, 2008), which claims the benefit ofU.S. Provisional Patent Application No. 60/950,706 (filed Aug. 19, 2007)and is a continuation-in-part of U.S. patent application Ser. No.11/457,697 (filed Jul. 14, 2006). U.S. patent application Ser. No.11/457,697 (filed Jul. 14, 2006) is a continuation-in-part of U.S.patent application Ser. No. 11/105,527 (filed Apr. 14, 2005), Ser. No.11/105,490 (filed Apr. 14, 2005), and Ser. No. 11/105,524 (filed Apr.14, 2005), all of which claim the benefit of U.S. Provisional PatentApplication 60/604,348 (filed on Aug. 25, 2004), and arecontinuations-in-part of U.S. patent application Ser. No. 10/087,856(tiled on Mar. 5, 2002), now U.S. Pat. No. 6,896,675. This applicationis also a continuation-in-part of U.S. patent application Ser. No.11/381,783 (filed on May 5, 2006). This application is also acontinuation-in-part of U.S. patent application Ser. No. 10/864,410(filed on Jun. 10, 2004). This application is also acontinuation-in-part of U.S. patent application Ser. No. 11/207,707(filed on Aug. 22, 2005). U.S. patent application Ser. No. 11/207,707 isa continuation-in-part of U.S. patent application Ser. No. 11/079,318(filed on Mar. 15, 2005) which is a continuation-in-part of U.S. patentapplication Ser. No. 10/382,836 (filed on Mar. 7, 2003). U.S. patentapplication Ser. No. 11/207,707 is also a continuation-in-part of U.S.patent application Ser. No. 11/125,247 (filed on May 10, 2005), which isa continuation-in-part of Ser. No. 10/853,126 (filed on May 26, 2004).This application also claims the benefit of U.S. Provisional PatentApplications 60/743,511 (filed on Mar. 16, 2006), 60/595,559 (filed onJul. 14, 2005), 60/595,560 (filed on Jul. 14, 2005), and 60/744,518(filed on Apr. 10, 2006). All of the aforementioned patents andapplications are incorporated herein by reference, in their entirety.

TECHNICAL FIELD

The invention relates to a method of electrosurgery. Specifically, theinvention relates to a method of electrosurgery for treating a thoracicregion of a spine of a patient's body.

BACKGROUND OF THE INVENTION

Radiofrequency energy is used in order to treat pain radiating fromnerves in the spine. Several prior-art approaches exist in order totarget an RF probe at the desired target location. However, regardlessof the approach used, a limitation of RF techniques is that the lesionforms immediately adjacent to the probe tip. Hence the efficacy of thetreatment is dependent upon the probe tip being in contact with or inclose proximity to the target nerve. The treatment may be ineffective ifthe probe is positioned in the general area of the target nerve but notadjacent to the nerve. This has been outlined in Bogduk et al.(Neurosurgery, 20(4): 529-535, 1987) as the reason for low success rateof RF neurotomy in the spine, “despite the accurate placement ofelectrodes onto anatomically correct target points, the lesions may notfully incorporate the nerve. The electrode tip may have rested close tothe nerve. However, RF electrodes coagulate circumferentially and onlyminimally distally, therefore the lesion may have been placedsuperficial to the nerve.” This problem is not limited to aperpendicular approach, as in the parallel approach even though “anelectrode lying parallel to the nerve is more likely to incorporate thenerve . . . this modification relies critically on the accurateplacement of the electrode”. Hence, the success of RF lesioning in thespine is dependent on the accurate positioning of the probe at thetarget nerve.

The thoracic region of the spine is a stable structure; thus a highprevalence of thoracic pain would not be expected. However, it has beenshown that between 15 and 24% of people suffering from spinal painexperience upper back/thoracic pain (Linton et al., 1998; Manchikantiand Pampati, 2002). Facet joint pain accounts for 42% to 48% of patientswith chronic thoracic pain (Manchikanti et al., 2004; Manchikanti etal., 2002). In summary, thoracic facet pain represents 6 to 12% of allspinal pain. Thus the present invention is directed to treating pain inthe thoracic region of the spine.

SUMMARY

The course of the nerves in the thoracic spine varies considerablybetween individuals as well as between the different thoracic levels.Thus, in order to create an effective lesion, the electrosurgical deviceneeds to be positioned to suit the varying anatomies. Embodiments of thepresent invention allow for effective treatment in the differentthoracic levels. The use of cooling with standard RF allows the lesionto be formed substantially distal to the tip of the electrosurgicalwhere the lesion forms between the electrosurgical device and thethoracic vertebra. This allows for effective lesioning of the targetnerve when the electrosurgical device is positioned at a distance fromthe nerve. This ensures that when the probe is positioned near thecourse of the target nerve, the resulting lesion encompasses the targetnerve. This provides an advantageous benefit not found in the prior art,in that it obviates the need for a probe to be placed in very closeproximity to a target nerve in order to effectively lesion the targetnerve. Thus, embodiments of the present invention are directed to asystem and method for providing an effective treatment of a target nervein the spine. More specifically, embodiments of the present inventionare directed to treating the thoracic region of the spine.

In one broad aspect embodiments of the present invention are directed toa method of treatment of a thoracic region of a patient's body, themethod comprising: positioning an energy delivery portion of anelectrosurgical device to face a segment of a thoracic vertebra at adistance from the segment; and cooling the energy delivery portion anddelivering energy through the energy delivery portion. As one feature ofthis aspect a lesion is formed at least substantially distal to theenergy delivery portion. As another feature of this aspect a lesion isformed at a location at least between the energy delivery portion andthe segment of the thoracic vertebra.

In another broad aspect embodiments of the present invention aredirected to a method of treatment of a thoracic region of a patient'sbody, the method comprising: inserting an introducer apparatus into thepatient's body, the apparatus comprising a cannula and an obturatordisposed within a lumen of the cannula, the obturator protruding from adistal end of the cannula; positioning the apparatus such that a distaltip of the obturator abuts a segment of a thoracic vertebra; removingthe obturator from within the cannula; inserting an electrosurgicaldevice within the cannula, to position an energy delivery portion of theelectrosurgical device at a distance from the segment of the thoracicvertebra; and delivering energy through the energy delivery portion andcooling the energy delivery portion, whereby a lesion forms at leastbetween the energy delivery portion and the segment of the thoracicvertebra.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be readily understood, embodiments ofthe invention are illustrated by way of examples in the accompanyingdrawings, in which:

FIG. 1A is a perspective view of an embodiment of an electrosurgicaldevice suitable for use with a method of the present invention;

FIG. 1B is a top view of the device of FIG. 1A;

FIG. 1C is a cross-sectional view of the device of FIG. 1A taken alongthe line 1C-1C in FIG. 1B;

FIG. 2 is a perspective view of an embodiment of a system suitable foruse with a method of the present invention;

FIG. 3A is a view of the thoracic vertebrae of a patient's spine,showing a target site for energy delivery;

FIGS. 3B-3D are lateral views of the thoracic vertebrae showing the pathof the nerves at the T1-T4, T5-T9 and T11-T12 thoracic levels;

FIG. 4 illustrates a position of an electrosurgical device with respectto the thoracic vertebrae in accordance with an embodiment of a methodof the present invention;

FIGS. 5A-5D illustrate steps involved in positioning an electrosurgicaldevice in accordance with an embodiment of a method of the presentinvention;

FIG. 6 is a view of the thoracic vertebrae of a patient's spine, showingan alternate target site for energy delivery;

FIG. 7 illustrates an alternate position of an electrosurgical devicewith respect to the thoracic vertebrae in accordance with an embodimentof a method of the present invention;

FIG. 8A illustrates the target location for inserting a spinal needle atthe transverse process in accordance with one embodiment of the presentinvention;

FIG. 8B is a lateral view of the thoracic vertebrae showing a spinalneedle at the transverse process, in accordance with an embodiment ofthe present invention;

FIG. 9A is a lateral view of the thoracic vertebrae showing anintroducer apparatus positioned at the tip of the spinal needle inaccordance with an embodiment of the present invention;

FIG. 9B is a lateral view of an electrosurgical device within a cannula,positioned at a distance from the transverse process in accordance withan embodiment of the present invention;

FIG. 9C is an oblique view of an electrosurgical device within acannula, positioned at a distance from the transverse process in aaccordance with an embodiment of the present invention;

FIG. 10A shows an anterior-posterior view of an electrosurgical deviceat a vertebra in the upper thoracic portion in accordance with anembodiment of the present invention;

FIG. 10B shows a lateral view of an electrosurgical device at a vertebrain the upper thoracic portion in accordance with an embodiment of thepresent invention;

FIG. 11A shows an anterior-posterior view of an electrosurgical deviceat a vertebra in the mid-thoracic portion in accordance with anembodiment of the present invention;

FIG. 11B shows a lateral view an electrosurgical device at a vertebra inthe mid-thoracic portion in accordance with an embodiment of the presentinvention;

FIG. 12A shows an anterior-posterior view of an electrosurgical deviceat vertebra in the lower-thoracic portion in accordance with anembodiment of the present invention;

FIG. 12B shows a lateral view of an electrosurgical device at vertebrain the lower-thoracic portion in accordance with an embodiment of thepresent invention;

FIG. 13A shows a lesion in accordance with one embodiment of the presentinvention; and

FIG. 13B shows a lesion in accordance with another embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

In one broad aspect, the present invention comprises a method fortreating a thoracic region of a spine of a patient's body, for examplein order to treat pain. Some embodiments of the method comprisepositioning an energy delivery portion of an electrosurgical device toface a segment of a thoracic vertebra at a distance from the segment;and cooling the energy delivery portion and delivering energy throughthe energy delivery portion. As a feature of this aspect a lesion isformed at least substantially distal to the energy delivery portion. Asanother feature of this aspect a lesion is formed at a location at leastbetween the energy delivery portion and the segment of the thoracicvertebra. In one feature of this aspect the energy delivery portionelectrosurgical device may be inserted and positioned in a relativelysafe, effective, and efficient manner. In one example, the energydelivery portion is positioned in proximity to a medial branch of athoracic dorsal ramus nerve and a lesion is formed at the medial branchof the dorsal ramus nerve. In some embodiments the lesion may formbetween the energy delivery device and a segment of the thoracicvertebra.

In another broad aspect, the embodiments of the present invention aredirected to a method of treatment of the thoracic region of a patient'sbody. Some embodiments of the method comprise inserting an introducerapparatus into the patient's body. The apparatus comprises a cannula andan obturator disposed within a lumen of the cannula such the obturatorprotrudes from a distal end of the cannula; positioning the apparatussuch that a distal tip of the obturator abuts a segment of the thoracicvertebra; and inserting an electrosurgical device within the cannulasuch that an energy delivery portion of the device is positioned at adistance from the segment of the thoracic vertebra. The method furthercomprises delivering energy through the energy delivery portion andcooling the energy delivery portion such that a lesion forms at leastbetween the energy delivery portion and the segment of the thoracicvertebra.

In another embodiment, a finder needle may be placed at thesuperior-lateral aspect to guide the placement of the introducerapparatus.

In some embodiments the electrosurgical device is positioned at asuperolateral aspect of a transverse process of a thoracic vertebra. Insome such embodiments, the electrosurgical device is inserted into thepatient's body such that at least a portion of the electrosurgicaldevice is generally upstanding relative to a portion of thesuperolateral aspect. In some such embodiments, inserting theelectrosurgical device comprises aligning the electrosurgical devicesuch that it is oriented substantially away from an anterior-posterioraxis of the patient's body, in a substantially cranial direction andadvancing the electrosurgical device into the patient's body towards thesuperior aspect of the transverse process. In one example of theembodiment, the electrosurgical device is positioned at a distance fromthe superior-lateral aspect. In one example the device is positionedsuch that an energy delivery portion of the device is facing thesuperior-lateral aspect of the transverse process. In some embodimentsthe lesion forms substantially distal to the energy delivery portion ofthe device.

In alternate embodiments, the electrosurgical device is inserted intothe patient's body such that at least a portion of the electrosurgicaldevice is positioned at a centroid of the transverse process. In somesuch embodiments, inserting the electrosurgical device comprisesaligning an electrosurgical device substantially with ananterior-posterior axis of a patient's body; advancing theelectrosurgical device into the patient's body towards the centroid ofthe transverse process; and positioning the energy delivery portion inproximity to the superolateral aspect of the transverse process. In oneexample of this embodiment the electrosurgical device is positioned at adistance from the superolateral aspect. In one example, the lesion formsat least substantially distal to the energy delivery portion of thedevice. In an example of this embodiment a lesion is formed between theenergy delivery portion and the superior-lateral aspect.

In further embodiments, the target site is a lamina of the thoracicvertebra. In some such embodiments, the electrosurgical device isinserted into the patient's body such that at least a portion of theelectrosurgical device is generally upstanding relative to a portion ofthe lamina. In some such embodiments, inserting the electrosurgicaldevice comprises aligning the electrosurgical device such that it isoriented substantially away from an anterior-posterior axis of thepatient's body, in a substantially lateral direction and advancing theelectrosurgical device into the patient's body towards the lamina.Further embodiments of the present invention are described herein below:

With specific reference now to the drawings in detail, it is stressedthat the particulars shown are by way of example and for purposes ofillustrative discussion of certain embodiments of the present inventiononly, and are presented in the cause of providing what is believed to bethe most useful and readily understood description of the principles andconceptual aspects of the invention. In this regard, no attempt is madeto show structural details of the invention in more detail than isnecessary for a fundamental understanding of the invention, thedescription taken with the drawings making apparent to those skilled inthe art how the several forms of the invention may be embodied inpractice.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

Device

Several embodiments of electrosurgical devices suitable for use withembodiments of the present invention are disclosed in U.S. patentapplication Ser. No. 11/457,697 (filed on Jul. 14, 2006), which isincorporated herein by reference. One particular embodiment of anelectrosurgical device suitable for use with embodiments of the presentinvention will presently be described. With reference first to FIG. 1A,an embodiment of a device suitable for use with embodiments of thepresent invention is probe 100. Probe 100 is an elongate member,comprising a shaft 122, a distal region 104, a distal end 106, aproximal region 108, and a proximal end 110. As used herein, the terms“distal” and “proximal” are defined with respect to the user and whenthe device is in use. That is, the term “distal” refers to the part orportion further away from the user, while the term “proximal” refers tothe part or portion closer to the user, when the device is in use.

Probe 100 defines a lumen 124. Proximal end 110 defines an aperture,which is in communication with lumen 124. Probe 100 comprises anelectrically insulated portion 116 and an electrically exposedconductive portion 118. Electrically exposed conductive portion 118 mayalso be referred to as an active electrode and is an example of an“energy delivery portion” mentioned herein.

The proximal region of probe 100 comprises a hub 114. Hub 114 isstructured to operatively connect other devices, such as connectorcables, cannulae, tubes, or other hubs, for example, to probe 100. Forexample, probe 100 may be coupled to an energy source and/or to a sourceof cooling via respective connecting means (for example, an electricalcable and/or flexible tubing) which may be associated with hub 114. Hub114 may also serve as a handle or grip for probe 100. Hub 114 may bemanufactured from a number of different materials, including, but notlimited to, plastics, polymers, metals, or combinations thereof.Furthermore, hub 114 may be attached to probe 100 by a number ofdifferent means. For example, in one embodiment, hub 114 may be madefrom polypropylene, and may be attached to probe 100 by insert molding.

The size of probe 100 may vary, depending upon which of the methodembodiments, described herein below, are used. In some embodiments, thelength from distal end 106 to proximal end 110 of probe 100 may bebetween about 5 cm and about 40 cm and the outer diameter of shaft 122may be between about 0.65 mm and about 2.00 mm (between about 20 G andabout 12 G). In one specific example, the length of the probe may beabout 7.5 cm and the outer diameter may be about 1.5 mm. Furthermore,the size and shape of active electrode 118 may vary, as is furtherdescribed in U.S. patent application Ser. No. 11/457,697, previouslyincorporated herein by reference. For example, in some embodiments,active electrode 118 may be between about 2 mm and about 8 mm in length.In other embodiments, active electrode 118 may comprise substantiallyonly the distal face of probe 100.

In some embodiments, electrically insulated portion 116 may be formed bycoating a portion of shaft 122 with an electrically insulative coating,covering, or sheathing. For example, in one particular embodiment, shaft122 of probe 100 may be fabricated from a biocompatible metal or alloy,for example stainless steel, which may be overlaid in part by aninsulating coating, for example polytetrafluoroethylene (PTFE). In otherembodiments, shaft 122 may be fabricated from another metal, such asnitinol or titanium, and/or the insulating coating may comprise adifferent electrically insulating material, including but not limited topolyethylene terephthalate (PET). In other embodiments, other metals orelectrically insulating materials may be used.

Probe 100 is structured such that it may be cooled by the internalcirculation of a cooling fluid. Such a configuration, whereby a coolingmedium does not exit from a distal region 104 of probe 100, may bereferred to as an internally-cooled probe. The cooling fluid may be anyfluid suitable for removing heat from probe 100 during surgery, forexample water. Other examples of cooling fluid include, but are notlimited to, liquid nitrogen and saline. Furthermore, the fluid may be atany temperature suitable for removing heat from the probe duringsurgery, for example between about 0° C. and about 25° C. Morespecifically, the temperature of the fluid may be at about roomtemperature (21° C.), about 4° C., or about 0° C., depending on theapplication.

The fluid may be delivered or circulated at a wide range of flow-rates.An appropriate flow-rate may be determined or calculated based on anumber of factors, including the conductivity and heat capacity of probe100, the cooling fluid and/or the tissue, and the desired temperature ofdistal end 106 of probe 100, among other factors. In some embodiments,the fluid may be delivered at between about 10 ml/min and about 30ml/min.

The internal structure of probe 100 is shown in FIG. 1C. The shaft ofprobe 100 defines a first lumen 124, and the proximal end 110 of probe100 is open and in communication with lumen 124. The distal end 106 ofprobe 100 is closed. Probe 100 further comprises an internal cannula,cylinder, or tube 130 disposed within lumen 124, defining a second lumen126. Internal tube 130 has an open distal end, which is locatedproximally to distal end 106 of probe 100, and an open proximal end. Theproximal end of internal tube 130 is structured to be operativelyconnected to a source of cooling fluid. For example, hub 114 may beoperable to connect internal tube 130 to a flexible tube. The proximalend of the flexible tube may be connected to the cooling source, forexample a reservoir of fluid, whereby the flexible tube functions as aninflow tube for cooling fluid from the reservoir to probe 100. Thus, inuse, fluid flows from the reservoir of fluid, through the flexible tube,and into internal tube 130. The fluid subsequently exits the distal endof internal tube 130, flows into lumen 124 of probe 100, and exits probe100 via open proximal end 110. Open proximal end 110 is coupled to meansfor disposing of the fluid or for returning the fluid to the reservoir.For example, another flexible tube may operatively connect proximal end110 to the reservoir, such that the flexible tube functions as anoutflow tube for the cooling fluid.

As mentioned hereinabove, one or more fluids may be delivered from areservoir to lumen 124 of probe 100 for the purposes of cooling probe100. The fluid(s) may be delivered to the probe 100 via a number ofmeans, and the invention is not limited in this regard. For example, inone embodiment and with reference to FIG. 2, the reservoir of fluid maycomprise a container, for example an intravenous (IV) bag 214, which iselevated above the patient. Tubing 216, for example clear plasticflexible tubing, may be used to connect the reservoir to an inlet inprobe 100. A valve 218 may be placed at the junction of the containerand the tubing (or at some other location between the container and theprobe), such that when the valve is opened, gravity may cause fluid toflow towards probe 100. After circulation within probe 100, fluid mayexit probe 100 via tubing, which may drain into another reservoir, forexample a second IV bag, or into a sink or other drain. In anotherembodiment, at least one pump may be used to deliver fluid to the probe100. For example, at least one peristaltic pump 210 may be operativelyconnected to a reservoir of fluid. The reservoir of fluid may be an IVbag, a polypropylene vial or burette, or another container, for example.The pump(s) may pump the fluid from the reservoir to an inlet in probe100. After circulating in probe 100, the fluid may exit the probethrough an outlet in probe 100 and may flow through a tube to either thesame or a different reservoir or, alternatively, to an alternatelocation as described above. A heat sink, heat exchanger, or othercooling source such as a refrigerant chiller may be used to cool thefluid after exiting the probe 100. A second pump, gravity, or a sourceof suction, for example, may assist in drawing the fluid out of theprobe 100.

With reference again to FIGS. 1A-1C, probe 100 comprises a temperaturesensing device 112. Temperature sensing device 112 may be any means forsensing and/or measuring temperature, including, but not limited to, athermocouple, a thermistor, an optical fluorescence sensor, and aresistance thermometer. Temperature sensing device 112 is positioned atthe distal region of probe 100, at distal end 106.

Probe 100 comprises means for operatively connecting temperature sensingdevice 112 to an external device. In some embodiments, such a device isa display or screen, such that the temperature measured by thetemperature sensing device may be viewed by a user. In otherembodiments, the external device is an electrical generator, such thattemperature feedback may be provided to the electrical generator. Meansfor operatively connecting temperature sensing device 112 to an externaldevice may comprise an insulated wire 128, which may extend proximallyfrom temperature sensing device 112, through a lumen of probe 100 (suchas the first lumen 124 as shown in FIG. 1C), and out of probe 100through proximal end 110. Wire 128 may be any temperature or electricalconductor capable of operatively connecting temperature sensing device112 to an external device. Alternatively, temperature sensing device 112may be operatively connected to an external device via a wirelessconnecting means, including, for example, infrared or Bluetooth®.Further details regarding temperature sensing devices may be found inU.S. patent application Ser. No. 11/105,490 (filed on Apr. 14, 2005),incorporated herein by reference.

With reference again to FIG. 2, an embodiment of a system suitable foruse with probe 100 may comprise one or more of: one or more introducerapparatuses 204, for example a cannula 204; one or more dispersivereturn electrodes (not shown); one or more sources of cooling, forexample pump 210; one or more energy sources, for example generator 208;and one or more connecting means, for example tube 212 and/or cable 213.

The introducer apparatus may aid in inserting probe 100 into a patient'sbody. The introducer apparatus may comprise a hollow elongate introduceror cannula 204 and an obturator 206. Further details regardingintroducer apparatuses are disclosed in U.S. patent application Ser. No.11/457,697 (filed on Jul. 14, 2006), previously incorporated herein byreference.

Probe 100 is structured to be operatively connected to an energy source,for example a generator 208. The connecting means for connecting probe100 to generator 208 may comprise any component, device, or apparatusoperable to make one or more electrical connections, for example aninsulated wire or cable. In one embodiment, the connecting meanscomprises an electrical cable 213 terminating at hub 114 as well as aconnector at a proximal end thereof. Cable 213 may be operable to coupleto energy source 208 directly or indirectly, for example via anintermediate cable. At least one wire or other electrical conductorassociated with cable 213 may be coupled to a conductive portion ofshaft 122, for example by a crimp or solder connection, in order tosupply energy from energy source 208 to shaft 122. In one specificembodiment, a 4-pin medical connector is used to connect cable 213 to anintermediate cable (not shown), which may be further attached to a14-pin connector capable of being automatically identified whenconnected to generator 208. Further details regarding such an embodimentare disclosed in U.S. patent application Ser. No. 10/122,413 (filed onApr. 16, 2002), incorporated herein by reference.

Generator 208 may produce various types of energy, for example microwaveor radio-frequency electrical energy. In some embodiments, generator 208produces radiofrequency electrical current, having a frequency ofbetween about 10 kHz and about 1000 kHz, at a power of between about 1 Wand about 50 W. An example of an RF generator that may be used as partof a system of the present invention is the Pain Management Generator(PMG) of Baylis Medical Company Inc. (Montreal, QC, Canada). Furtherdetails regarding embodiments of energy sources are disclosed in U.S.patent application Ser. No. 11/457,697 (filed on Jul. 14, 2006),previously incorporated herein by reference.

As mentioned hereinabove, in some embodiments, one or more peristalticpumps 210 are used to supply a cooling fluid to and return a coolingfluid from probe(s) 100. In other embodiments, other types of pumps maybe used. Examples include, but are not limited to, a centrifugal pump ora piston pump. As mentioned above with respect to temperature control,controlling the delivery of a cooling fluid, or other cooling means, maybe performed for each probe independently, or the cooling may becontrolled based on an average temperature measurement or a measurementrecorded from one probe, for example. Further details regarding thecooling source are provided in U.S. patent application Ser. No.11/105,527 (filed on Apr. 14, 2005) and Ser. No. 10/864,410 (filed onDec. 10, 2005).

Methods

Embodiments of a method of the present invention allow for the creationof a lesion between an energy delivery portion of an electrosurgicaldevice and some predetermined location, such as a segment of a thoracicvertebra. For example, a lesion may be created substantially distal toand facing the energy delivery portion by delivering energy to theenergy delivery portion and cooling the energy delivery portion. Thisprovides an advantageous benefit not found in the prior art, in that itobviates the need for a probe 100 to be placed in very close proximityto a target nerve in order to effectively lesion the target nerve.

In one broad aspect, an embodiment of a method of the present inventioncomprises positioning an energy delivery portion of an electrosurgicaldevice to face a segment of a thoracic vertebra at a distance from thesegment; and cooling the energy delivery portion and delivering energythrough the energy delivery portion whereby a lesion is formed at leastsubstantially distal to the energy delivery portion. In some embodimentsthe lesion is formed at a location at least between the energy deliveryportion and the segment of the thoracic vertebra.

In one broad aspect, the present invention comprises a method fortreating a thoracic region of a spine of a patient's body, for examplein order to treat pain. Some embodiments of the method compriseinserting an electrosurgical device into a patient's body andpositioning an energy delivery portion of the electrosurgical device inproximity to a medial branch of a thoracic dorsal ramus nerve such thatthe energy delivery portion is positioned at a distance from and facinga segment of a thoracic vertebra; delivering energy through and/whilecooling the energy delivery portion to create a lesion at the medialbranch of the thoracic dorsal ramus nerve. Preferably the lesion formsat least substantially distal to the energy delivery portion. In oneexample of the embodiment, the lesion forms between the energy deliveryportion and a segment of the thoracic vertebra. As a feature of thisaspect, the electrosurgical device may be inserted and positioned in arelatively safe, effective, and efficient manner.

In another broad aspect the embodiments of the present invention aredirected to a method of treatment of the thoracic region of a patient'sbody where the method comprises inserting an introducer apparatus intothe patient's body. The apparatus comprises a cannula and an obturatordisposed within a lumen of the cannula the obturator protruding from adistal end of the cannula. The apparatus is positioned such that adistal tip of the obturator abuts a segment of the thoracic vertebra. Anelectrosurgical device is then inserted within the cannula to positionan energy delivery portion of the device at a distance from the segmentof the thoracic vertebra. The method further comprises delivering energythrough the energy delivery portion and cooling the energy deliveryportion whereby a lesion forms at least between the energy deliveryportion and the segment of the thoracic vertebra.

In one embodiment of the present invention a marker is used in order toposition the electrosurgical device. In some embodiments the marker maybe used in order to position an introducer apparatus. Some embodimentsof the method comprise positioning a marker such that a distal end ofthe marker abuts a segment of a thoracic vertebra, the markerfunctioning as a visual reference for positioning an electrosurgicaldevice. When viewed under imaging, an electrosurgical device such asprobe is advanced towards the marker to position the distal tip of thedevice at the distal end of the marker.

In some embodiments the target site is a superolateral aspect of atransverse process of a thoracic vertebra. In some such embodiments, theelectrosurgical device is inserted into the patient's body such that atleast a portion of the electrosurgical device is generally upstandingrelative to a portion of the superolateral aspect. In some suchembodiments, inserting the electrosurgical device comprises aligning theelectrosurgical device such that it is oriented substantially away froman anterior-posterior axis of the patient's body, in a substantiallycranial direction and advancing the electrosurgical device into thepatient's body towards the superior aspect of the transverse process.The electrosurgical device is positioned such that the energy deliveryportion of the device is at a distance from the superior-lateral portionof the transverse process. In one embodiment the energy delivery portionis cooled substantially while delivering energy, such a lesion forms atleast substantially distal to the energy delivery portion.

In alternate embodiments, the electrosurgical device is inserted intothe patient's body such that at least a portion of the electrosurgicaldevice is positioned at a centroid of the transverse process. In somesuch embodiments, inserting the electrosurgical device comprisesaligning an electrosurgical device substantially with ananterior-posterior axis of a patient's body; advancing theelectrosurgical device into the patient's body towards the centroid ofthe transverse process; and positioning the energy delivery portion isin proximity to the superolateral aspect of the transverse process. Thedevice is positioned such that an energy delivery portion of the deviceis positioned at a distance from the superolateral aspect of thetransverse process. In one embodiment, the energy delivery portion ofthe device is cooled substantially while delivering energy, such that alesion extends between the energy delivery portion and the superolateralaspect. In one example the lesion is formed at least substantiallydistal to the energy delivery portion.

In further embodiments, the target site is a lamina of the thoracicvertebra. In some such embodiments, the electrosurgical device isinserted into the patient's body such that at least a portion of theelectrosurgical device is generally upstanding relative to a portion ofthe lamina. In some such embodiments, inserting the electrosurgicaldevice comprises aligning the electrosurgical device such that it isoriented substantially away from an anterior-posterior axis of thepatient's body, in a substantially lateral direction and advancing theelectrosurgical device into the patient's body towards the lamina. Inaddition to embodiments described above, further embodiments of thepresent invention will be described hereinbelow.

In one specific embodiment of the present invention, a method oflesioning a medial branch of a dorsal ramus nerve in a thoracic regionof a patient's body is provided, the method comprising: visualizing athoracic vertebra of the patient's body along an anterior-posterior axisof the patient's body using fluoroscopic imaging; positioning a spinalneedle at a superolateral aspect of a transverse process of the thoracicvertebra under guidance of the fluoroscopic imaging; visualizing thethoracic vertebra along an axis about 45 degrees caudal to theanterior-posterior axis; inserting an introducer apparatus into thepatient's body along the axis about 45 degrees caudal to theanterior-posterior axis, the introducer apparatus comprising anobturator disposed within a lumen of a cannula, the obturator protrudingfrom a distal end of the cannula by about 7.5 mm; guiding the introducerapparatus towards a tip of the spinal needle; positioning a distal tipof the obturator in abutting relation to the superolateral aspect of thetransverse process, in proximity to the tip of the spinal needle;removing the obturator from the lumen of the cannula; inserting anelectrosurgical device through the lumen of the cannula, theelectrosurgical device having an energy delivery portion at a distal tipof the electrosurgical device, the electrosurgical device protrudingfrom the distal end of the cannula by about 5.5 mm, whereby the energydelivery portion of the electrosurgical device is facing thesuperolateral aspect of the transverse process and is located about 2 mmaway from the superolateral aspect of the transverse process; anddelivering radiofrequency electrical energy to the energy deliveryportion of the electrosurgical device while cooling the energy deliveryportion of the electrosurgical device.

Referring now to FIG. 3A, a brief description of the typical anatomy ofthe thoracic region of the spine is provided. The vertebrae 300 of thethoracic region of the spine are intermediate in size between those ofthe cervical and lumbar regions; the upper thoracic vertebrae beingsmaller than those in the lower part of the thoracic region. Thevertebral bodies are generally as broad in the anterior-posterior as inthe transverse direction. At the upper and lower ends of the thoracicregion the vertebral bodies resemble respectively those of the cervicaland lumbar vertebrae. As shown in FIG. 3A, the pedicles of the thoracicvertebrae 300 are directed backward and slightly upward. The spinousprocess 308 is long and extends posterior and caudal, and ends in atuberculated extremity. The thoracic facet joints are paired jointslocated between the superior 302 and inferior 304 articular processes ofadjacent vertebrae. The superior articular processes 302 are thin platesof bone projecting upward from the junctions of the pedicles and laminae316; their articular facets are practically flat, and are directedposteriorly and slightly lateral and upward. The inferior articularprocesses 304 are fused to a considerable extent with the laminae 316,and project slightly beyond their lower borders; their facets aredirected anteriorly and slightly medial and downward. The transverseprocesses 306 arise from the arch behind the superior articularprocesses 302 and pedicles; they are directed obliquely backward andlateral.

The thoracic facet joints are innervated by the medial branches of thedorsal rami. The medial branches pass between consecutive transverseprocesses 306 and head medially and inferiorly, passing through thecentroid region 314 of the transverse process 306. The medial branchesinnervate the facet joint at the level of their respective spinal nerveand the two facet joints below. For example, the T1 medial branchinnervates both the T1-T2 as well as the T2-T3 facet joints. At T1 to T4and T9 and T10, the medial branches cross the superior-lateral aspect318 of the transverse process 306. At T5 to T8, the medial branchesfollow a similar course, but may remain suspended within theintertransverse space. At T11 and T12, the medial branch has a courseakin to the lumbar medial branches such that they course posteriorlyalong the medial aspect of the transverse process 306, at the root ofthe superior articular process 302.

The medial branches of the dorsal rami assume a reasonably constantcourse for the upper thoracic and lower levels. Mid-thoracic medialbranches follow a much more variable course and do not have a consistentosseous relation.

Two types of articular branches arise from the medial branches.Ascending branches arise from the medial branch as it passes caudal tothe facet joint. These branches are short and they ramify in theinferior aspect of the facet joint capsule. A slender descendingarticular branch arises from the medial branch as it crosses thesuperolateral corner 318 of the transverse process 306. It follows asinuous course between the fascicles of multifidus to reach the superioraspect of the capsule of the facet joint below (Chua and Bogduk, 1995).Thus, thoracic facet joints, much like lumbar facet joints, receivebisegmental innervation from medial branches of dorsal ramus of theupper segment and one or more cephalad levels. For example, the T5medial branch innervates the T5-6 and T6-7 facets.

Typically, in the T1-4 and T9-10 levels, the medial branch arises fromthe dorsal ramus within 5 mm of the lateral margin of the intervertebralforamen. The region 320 where the nerve is likely to be found is shownin FIGS. 3B and 3D. Upon leaving the intertransverse space, the medialbranch 321 crosses the superolateral corner 318 of the transverseprocess 306 at its inflection point and then passes medially andinferiorly across the posterior surface of the transverse process 306before ramifying into the multifidus muscles (not shown). Variabilitybetween individuals is minimal for the T1-T4 medial branches near thesuperolateral corner 318 of subjacent transverse process. Also,variability decreases greatly near the bone surface. The variability inthe course of the medial branch is shown by the medial branches 321 a,321 b and 321 c of varying anatomies. Variability between individuals isminimal for the T9-T10 medial branches near the superolateral corner ofsubjacent transverse process as shown in FIG. 3D. The variabilitydecreases greatly near the surface of the bone as shown by the path ofthe nerves in region 322. The reference numerals 321 a, 321 b and 321 cindicate variable course of the nerve 321 in different individuals.

In the mid-thoracic levels from T5-8 as shown in FIG. 3C, exceptions tothe archetypical course occur where, although the course is parallel,the nerve may be displaced superiorly and therefore may not contact thetransverse process 306 (Chua and Bogduk, 1995). The likely course of thenerve is indicated by the region 330. Treatment at these levels ischallenging as the nerve lacks a consistent osseus relation, which makeslandmarking difficult. Variability between individuals is significantfor the T5-T8 medial branch 331 near the superolateral corner ofsubjacent transverse process. The location of the medial branch may varyas indicated by the medial branches 331 a, 331 b and 331 c in varyinganatomies. Reference numerals 321 a, 321 b and 321 c indicate variablecourse of the nerve 321 in different individuals.

At the T11 level, the medial branch runs across the lateral surface ofthe root of the superior articular process of the T12 (Chua and Bogduk,1995). The T12 transverse process is much shorter than typicaltransverse processes. The T12 medial branch assumes a course analogousto the lumbar medial branches crossing the junction of the superiorarticular process and the transverse process (Chua and Bogduk, 1995).

Due to the varied course of the medial branch across the 12 thoraciclevels, the lack of bony landmarks associated with the thoracic medialbranch, and the anatomic differences among patients, it is oftenrequired to create several lesions in order to denervate one thoracicfacet joint, as described by Dreyfuss et al (ISIS Newsletter, December1997, Volume 2, Number 6). Embodiments of the present invention allowfor the formation of a relatively large lesion for denervating a facetjoint or for treating other pathologies associated with a medial branch,for example musculocutaneous or muscular pain, thus providing a morestraightforward, safer, more effective and less invasive procedure.

Embodiments of a method of treating thoracic pain in accordance with thepresent invention will be presently described in greater detail. Thedescription will reference the anatomy of the first through tenththoracic vertebrae. In some embodiments, the target site for treatingthoracic pain may comprise the nerves innervating the facet joint, i.e.the medial branches of the dorsal rami. As described hereinabove, thesenerves may be located substantially laterally, between two consecutivetransverse processes, or substantially adjacent the superior edge of atransverse process. Thus, in a first embodiment, the target site 310 forenergy delivery may be the superolateral aspect 318 of the transverseprocess of a thoracic vertebra and the region immediately superiorthereto.

The path of the nerves in the thoracic spine varies between thedifferent thoracic levels. The path can also vary considerably betweendifferent individuals. Thus, in order to create an effective lesion, theelectrosurgical device needs to be positioned to match the varyinganatomies.

Embodiments of the present invention allow for effective treatment inthe different thoracic levels. The use of cooling with standard RFallows the lesion to be formed substantially distal to the tip of theelectrosurgical device. In some embodiments the lesion forms between theelectrosurgical device and the thoracic vertebra. Furthermore, it allowsfor effective treatment of the target nerve when the electrosurgicaldevice is positioned at a distance from the nerve. This ensures that theresulting lesion encompasses the target nerve, when the probe ispositioned near the course of the target nerve. Thus embodiments of thepresent invention are directed to a system and method for providing aneffective treatment of a target nerve in the thoracic region of thespine. More specifically, the method is directed to positioning anenergy delivery portion of a device at a distance from a segment of athoracic vertebra. and cooling the energy delivery portion such that alesion forms substantially distal to the energy delivery portion.

As described in U.S. patent application Ser. No. 11/457,697, previouslyincorporated herein by reference, in some embodiments, the step ofinserting the electrosurgical device may comprise the use of anintroducer apparatus to position the electrosurgical device at adistance from a segment of the thoracic vertebra. The apparatus maycomprise a cannula and an obturator, for example. In use, the obturatormay be initially disposed within a lumen of the cannula to facilitateinsertion of the introducer apparatus to the target treatment site. Oncethe introducer apparatus has been properly positioned, the obturator maybe removed and replaced within the cannula lumen by the electrosurgicaldevice. Thus, rather than inserting and positioning the electrosurgicaldevice as described hereinabove, the user may insert and position anintroducer apparatus as described hereinabove. The user may then removethe obturator from the cannula, and insert the electrosurgical devicethrough the cannula. For example, in the embodiment shown in FIG. 4, theuser may insert an introducer apparatus such that it is generallyupstanding relative to the superolateral aspect 318 of the transverseprocess 306, and advance the introducer apparatus until the distal endof the obturator contacts the superolateral aspect 318 of the transverseprocess 306. The user may then withdraw the obturator from the cannula,and insert electrosurgical device 400 into the cannula, such that energydelivery portion 402 is at or adjacent target site 310. In embodimentswherein an introducer apparatus is not used, electrosurgical device 400may have a substantially sharp tip, and thus may be inserted andpositioned as shown in FIGS. 4-7.

In some particular embodiments, wherein an introducer apparatus is used,the introducer apparatus and the electrosurgical device may bestructured such that the obturator protrudes a greater distance from thedistal end of the cannula than the electrosurgical device does, whenfully inserted through the cannula, as described in U.S. patentapplication Ser. No. 11/733,515 (filed on Apr. 10, 2007), incorporatedherein by reference. In such an embodiment, the introducer apparatus maybe advanced until the distal end of the obturator contacts bone, forexample the superolateral aspect 318 of the transverse process. Theobturator may then be removed from the cannula, leaving the cannula inplace, and the electrosurgical device may be inserted into the cannula.Due to the difference in length of the obturator and the electrosurgicaldevice, when the electrosurgical device is fully inserted into thecannula, a gap will exist between the distal end of the electrosurgicaldevice and the transverse process. The existence of this gap may ensurethat when energy is delivered from the electrosurgical device, thelesion created does not extend too deeply into the bone thus limitingany unwanted necrosis of the bone. In addition, such an embodiment mayallow for fluoroscopic visualization of an intended location of lesionformation, as is further detailed in U.S. patent application Ser. No.11/733,515 (filed on Apr. 10, 2007), previously incorporated herein byreference. In one example of this embodiment the difference in thelength of the electrosurgical device and the obturator is between about0.5 mm to about 4 mm. Hence the energy delivery portion of theelectrosurgical device is located at a distance of about 0.5 mm to about4 mm away from the transverse process. In one particular example, thedistance between the energy delivery portion and the transverse processis about 2 mm.

In some embodiments a marker may be used to assist in positioning anintroducer apparatus. In some embodiments the marker may be used toposition an electrosurgical device. The marker may be used in medicalprocedures requiring real-time imaging to aid in the positioning ofmedical devices at locations within a patient's body. More specifically,the marker may be used in regions of the body having few anatomicalstructures (such as bone) that are visible during imaging. In these bodyregions a landmark is not available to assist in positioning the device.Thus, while positioning an electrosurgical device, it may be difficultto ascertain if the device has penetrated a region of the body otherthan the target location. In some medical procedures, it is critical toavoid certain anatomical structures that are in close proximity to thetarget site. Thus, use of a marker to position the device may make theprocedure safer and more effective. In some embodiments, the marker is aneedle. More specifically, the needle, in some embodiments, is a finderneedle. In other embodiments the needle may be a spinal needle. Theneedle can be inserted into the patient's body such that the distal endof the needle marks a target location. The needle may partially or fullycomprise a radiopaque material. For example, in one embodiment theneedle may comprise a radiopaque marker band at its distal end. The bandmay comprise of a radiopaque material such as platinum or tungsten. Inother embodiments the needle may comprise stainless steel. When viewedunder imaging, an electrosurgical device such as probe can then beadvanced towards the needle such that an energy delivery portion of thedevice is positioned at or near the distal end of the needle, forexample at a distance from a region of the thoracic vertebra. In oneexample, as described hereinabove, the energy delivery portion of theelectrosurgical device is at its distal tip.

Referring specifically now to FIGS. 8A-8B, in one embodiment, a spinalneedle 800 may be used to guide the placement of the probe at thesuperolateral aspect 318 of the transverse process as illustrated inFIGS. 8A-8B. The distal end of the needle contacts a point 802 on thesuperior lateral outer third 804 on the posterior surface of thetransverse process substantially towards the superior margin. Moregenerally the needle is placed in the superior lateral quadrant of thetransverse process. Before placement of the needle, theAnterior-Posterior image is aligned with the desired vertebral levelusing an imaging modality. In one example standard X-ray fluoroscopy isused. The needle which can be a thin spinal needle is placed on thepatient's skin at a point above the superior lateral outer third 804 ofthe transverse process 806. The needle is then inserted into thepatient's skin, and advanced until the tip 808 touches the transverseprocess 806. A lateral image is then obtained and placement of theneedle ensures that the desired depth of the insertion of the probe isvisible and is marked by the tip of the needle.

Once the needle has been positioned at the desired target location onthe superior lateral quadrant of the transverse process, a medicalinstrument, for example, an introducer is used to find a suitable skininsertion point. The skin is nudged or depressed slightly using theinstrument in order to visualize the insertion point using the lateralview. Using live fluoroscopy the angle of the introducer is adjusteduntil the tip 808 of the spinal needle is in the projected path of theintroducer. The introducer is then removed and an introducer apparatusis inserted at the insertion site and its angle is adjusted such thatthe distal end of the introducer apparatus is targeted at the needle tip808. The introducer apparatus is then advanced towards the tip of thespinal needle. The spinal needle helps prevent the device from beingadvanced further than the target site and reduces the risk of pleuralpuncture. In another example of the present embodiment the finder needlemay be positioned on the lateral edge of the transverse process.

The introducer apparatus is of the kind discussed previously in FIG. 4and comprises an obturator 904 within the cannula 912. In one example ofthe present embodiment as illustrated in FIG. 9A, after the spinalneedle has been positioned at the superior-lateral aspect of thetransverse process, the C-arm is rotated 45° cranially. Using a gunbarrel approach, the introducer apparatus is advanced towards the tip808 of the spinal needle under an Anterior-Posterior view. The apparatusis advanced until the obturator 904 touches the superior-lateral corner918 of the transverse process 906 in proximity to the tip 808 of thespinal needle. After introducer placement, a lateral view is obtained toconfirm appropriate positioning and depth.

The obturator is then removed and an electrosurgical device 900 isinserted into the cannula. The electrosurgical device protrudes a lesserdistance from the distal end of the cannula than the obturator as shownin FIGS. 9B and 9C. As a result the distal tip 902 of theelectrosurgical device is positioned a distance away from thesuperior-lateral aspect of the transverse process. Hence, the differencebetween the length of the obturator 904 and the electrosurgical device900, automatically positions the device 900 such that the lesion formsat least partially in the intertransverse space. Energy is deliveredfrom the distal tip of the device and the device is cooled, such that alesion forms at least substantially distal to the distal tip 902 of thedevice. In one example the lesion is formed between the device distaltip 902 and the superior-lateral aspect. Additionally, use of the needlereduces the risk of pleural puncture as the device is not advanced pastthe distal end of the needle. In some embodiments an electrosurgicaldevice may be inserted directly without the aid of an introducerapparatus. The electrosurgical apparatus may be positioned in a similarmanner described above for the introducer apparatus with the aid of aspinal needle.

Various embodiments of the method of the present invention will bepresently described, referring to various points/angles of insertion aswell as various desired positions of the energy delivery portion of theelectrosurgical device.

In some embodiments of the present invention an electrosurgical devicemay be inserted to the superior-lateral corner of the transverseprocess, as shown in FIG. 4. In some embodiments the electrosurgicaldevice is inserted with the aid of an introducer apparatus as discussedpreviously herein. In some embodiments the patient may be placed in theprone position in preparation for the treatment procedure. The user mayoptionally administer various treatments, such as anesthetics orantibiotics, for example. In addition, as described above, the user mayoptionally insert a spinal needle into the patient's body, at thelateral edge of the transverse process, in order to act as a visualmarker when the patient's body is visualized from angles other than theanterior-posterior view using a medical imaging system, for example afluoroscopic system. The user may then insert at least oneelectrosurgical device 400, having an energy delivery portion 402,percutaneously toward the target site. In some embodiments,electrosurgical device 400 may be probe 100 described hereinabove. Inother embodiments, electrosurgical device 400 may be, for example, analternate device as described in U.S. patent application Ser. No.11/457,697, previously incorporated herein by reference.

Prior to inserting electrosurgical device 400 into the patient's body,electrosurgical device 400 may be positioned at a point of insertion ona surface of the patient's body, for example on the dorsal surface. Inone embodiment, the point of insertion on the patient's body may be theregion that is substantially laterally aligned with a location medial toa lateral edge of the transverse process of the underlying thoracicvertebra.

When the electrosurgical device 400 has been positioned at the point ofinsertion, the electrosurgical device 400 may be inserted into the body.In one embodiment, electrosurgical device 400 may be inserted such thatat least a portion of the electrosurgical device is generally upstandingrelative to a superolateral aspect 318 of a transverse process 306 of athoracic vertebra. As used herein, the term ‘generally upstanding’refers to an angle that is between about 45° and about 135° from thehorizontal plane. More specifically, in some embodiments, the term‘generally upstanding’ may refer to an angle of between about 75° andabout 105° from the horizontal plane. In some particular embodiments,the term ‘generally upstanding’ may refer to an angle of about 90° fromthe horizontal plane. In some embodiments, wherein the electrosurgicaldevice is bent or curved, as described in U.S. patent application Ser.No. 11/457,697 (filed on Jul. 14, 2006), previously incorporated hereinby reference, the portion of the electrosurgical device that is distalto the bend or curve may be generally upstanding relative to thesuperolateral aspect 318 of the transverse process 306. In order toposition electrosurgical device 400 such that it is generally upstandingrelative to a superolateral aspect 318 of a transverse process 306 of athoracic vertebra, electrosurgical device 400 may be angled such that itis oriented substantially away from an anterior-posterior (AP) axis 450of the body, in a substantially cranial direction. In some embodiments,the electrosurgical device may be oriented at an angle of between about15° and about 60° away from the AP axis in a substantially cranialdirection. More specifically, electrosurgical device 400 may be orientedat an angle of about 45° away from the AP axis, in a substantiallycranial direction. Electrosurgical device 400 may be advanced until itcontacts the superolateral aspect of the transverse process, such thatenergy delivery portion 402 is in proximity to the target site 310. Theenergy delivery portion is positioned at a distance from thesuperior-lateral aspect of the transverse process. In one embodiment anenergy delivery portion of the electrosurgical device is positionedwherein is positioned at a location in the region bounded by a superiormargin of the transverse process, an inferior margin of a superjacenttransverse process, an anterior margin of the transverse process and ananterior margin of the superjacent transverse process, a posteriormargin of a spinous process of the thoracic vertebra, an inferiorarticular process of the thoracic vertebra and a superior articularprocess of a superjacent thoracic vertebra, a lateral margin of thetransverse process and a lateral margin of the superjacent transverseprocess.

When energy is applied to the energy delivery portion and it issubstantially cooled, a lesion forms substantially distal to the energydelivery portion. The lesion is formed such that a significant portionof the lesion forms distal to the energy delivery portion.

Referring to FIGS. 5A-5C, in an alternate embodiment, electrosurgicaldevice 400 may be inserted into the patient's body such that it issubstantially aligned with the AP axis 450 of the patient's body. Insuch an embodiment, electrosurgical device 400 may be inserted until thedistal end contacts the centroid region 314 of the transverse process306, as shown in FIG. 5A. In some embodiments and introducer apparatusmay be used in order to position the electrosurgical device as discussedherein above. When electrosurgical device 400 contacts the centroidregion 314 of the transverse process 306, a depth stopper 415, shown inFIG. 5B, may be placed on electrosurgical device 400 at the position onelectrosurgical device 400 that is adjacent to the surface of thepatient's skin (not shown). Electrosurgical device 400 may then bewithdrawn slightly, for example by about 1 mm to about 5 mm. The usermay then move electrosurgical device 400 in a substantially cranialdirection until the distal end of electrosurgical device 400 is adjacentthe superolateral aspect 318 of the transverse process 306. In otherwords, the user may “walk” the electrosurgical device in the cranialdirection, until the distal end of the electrosurgical device slips overthe superolateral aspect 318 of transverse process 306. Theelectrosurgical device may then be advanced slightly, until depthstopper 415 on electrosurgical device 400 is again adjacent the surfaceof the patient's skin, as shown in FIG. 5C, such that an energy deliveryportion, for example the energy delivery portion 402 is in proximity toa target site. The electrosurgical device is positioned such that theenergy delivery portion is positioned at a distance from thesuperolateral aspect. Energy is delivered from the energy deliveryportion and the energy delivery portion is substantially cooled suchthat a lesion forms substantially distal to the energy delivery portion.

Alternatively, in some such embodiments, a user may insert a secondelectrosurgical device into the patient's body, at the vertebra that isimmediately superior to the vertebra where the first electrosurgicaldevice was inserted. For example, if the first electrosurgical devicewas inserted at T5, the second electrosurgical device may be inserted atT4. The second electrosurgical device may be inserted in the same manneras described with reference to FIGS. 5A-5C; however, rather than walkingthe second electrosurgical device in a cranial direction, the secondelectrosurgical device 500 may be walked in a caudal direction until thesecond electrosurgical device begins to slip over the inferolateralaspect 312 of the transverse process as shown in FIG. 5D. Thus, thefirst and second electrosurgical devices will be positioned at eitherend of an intertransverse space of adjacent vertebrae. In such anembodiment, energy may be delivered in a bipolar manner, such that alesion 504 forms substantially between the first electrosurgical deviceand the second electrosurgical device. In some embodiments, the order ofinsertion is reversed, i.e. the first electrosurgical device is insertedto a thoracic vertebra and walked in a caudal direction and the secondelectrosurgical device is inserted to the immediately inferior vertebraand is walked in a cranial direction.

In a further alternate embodiment, electrosurgical device 400 may beinserted into the patient's body such that it is tilted substantiallyaway from the AP axis 450 of the patient's body, in a substantiallycaudal direction. In some embodiments, the electrosurgical device may beoriented at an angle of between about 15° and about 60° away from the APaxis 450 in a substantially caudal direction. More specifically,electrosurgical device 400 may be oriented at an angle of about 45° awayfrom the AP axis, in a substantially caudal direction. In such anembodiment, electrosurgical device 400 may be inserted until the distalend contacts the centroid region 314 of the transverse process 306. Whenelectrosurgical device 400 contacts the centroid region 314 of thetransverse process 306, a depth stopper 415 may be placed onelectrosurgical device 400 at the position on electrosurgical device 400that is adjacent to the surface of the patient's skin (not shown).Electrosurgical device 400 may then be withdrawn slightly, for exampleby about 1 mm to about 5 mm. The user may “walk” the electrosurgicaldevice in the cranial direction, until the distal end of theelectrosurgical device begins to slip over the superolateral aspect 318of transverse process 306. The electrosurgical device may then beadvanced slightly, until depth stopper 415 on electrosurgical device 400is again adjacent the surface of the patient's skin. Due to the caudaltilt of electrosurgical device 400, energy delivery portion 402 willextend substantially into the intertransverse space such that it ispositioned at a distance from the superior-lateral aspect. Afterpositioning the device, energy is delivered from the energy deliveryportion and the energy delivery portion is cooled, such that a lesionforms at least substantially distal to the energy delivery portion.

The introducer apparatus discussed previously may be particularly usefulin the embodiment described above wherein the electrosurgical device isoriented caudally away from the AP axis 450 of the patient's body,inserted towards the centroid of the transverse process, and walkedcranially such that the energy delivery portion extends into theintertransverse space. Similar to the embodiments disclosed previously,the use of a longer obturator to position the cannula helps to minimizethe depth into the intertransverse space to which the electrosurgicaldevice extends, thus providing a safer procedure. In other words, thecannula and obtruator are inserted until the obturator contacts thecentroid, at which point a depth stopper may be positioned on thecannula at the patient's skin. The introducer apparatus (i.e. thecannula and obturator) is then walked cranially until theintertransverse space is reached. The obturator is then removed, leavingthe cannula in place. When the electrosurgical device is thereafterinserted through the cannula, it will not extend substantially into theintertransverse space, since it is shorter than the obturator, thusresulting in a safer procedure. In some embodiments the electrosurgicaldevice is about 0.5 to about 5 mm shorter than the obturator. Thus, theuse of an obturator that is longer that the electrosurgical device,allows for the positioning of the electrosurgical device at a distanceaway from a segment of a thoracic vertebra in accordance with theembodiments of the present invention. In one example the difference inthe length of the obturator and the electrosurgical device is about 2mm, allowing for the positioning of the electrosurgical device at adistance of about 2 mm from the superior-lateral aspect.

In an alternate embodiment, the target site 310 may not be thesuperolateral aspect 318 of the transverse process and the regionimmediately superior thereto. Rather, the target site 310 may be thelamina 316 of the vertebra 300, as shown in FIG. 6, where the medialbranch of the dorsal rami branches into the ascending and descendingbranches of the dorsal rami. Referring to FIG. 7, wherein a thoracicvertebra is shown from a cranial view looking along the coronal plane,in this embodiment, the electrosurgical device 400 may be inserted intothe patient's body such that it is generally upstanding relative to thelamina 316 of the vertebra 300. In some embodiments an electrosurgicaldevice may be positioned with the aid of an introducer apparatus asdiscussed previously. In order to position electrosurgical device 400such that it is generally upstanding relative to the lamina 316 of thethoracic vertebra 300, electrosurgical device 400 may be angled suchthat it is oriented substantially away from an anterior-posterior (AP)axis 450 of the body, in a substantially lateral direction. In someembodiments, the electrosurgical device may be oriented at an angle ofbetween about 15° and about 65° away from the AP axis in a substantiallylateral direction. More specifically, electrosurgical device 400 may beoriented at an angle of about 45° away from the AP axis, in asubstantially lateral direction. Electrosurgical device 400 may then beinserted until it contacts the lamina 316. This embodiment may be usefulin cases where the user is particularly concerned about causingpneumothorax in the patient. That is, since the electrosurgical deviceis directed at the lamina 316, and not towards the intertransversespace, there may be a decreased risk of accidentally puncturing thepleural sac of the patient.

In an alternate embodiment, a user may insert a second electrosurgicaldevice into the patient's body. The second electrosurgical device may beinserted at the same vertebral level as the first electrosurgicaldevice. In such an embodiment, the second electrosurgical device may beinserted in the same manner as described hereinabove with reference toFIG. 7; however, the second electrosurgical device may be inserted suchthat it is positioned at a distance from the first electrosurgicaldevice. For example, the first electrosurgical device may be positionedas described above with reference to FIG. 7, and the secondelectrosurgical device may be positioned superior to the firstelectrosurgical device, at a distance of between about 0.1 cm to about 2cm away from the first electrosurgical device. In some particularembodiments, the first and second electrosurgical devices are positionedabout 1 cm apart from each other. In these embodiments, energy may bedelivered in a bipolar manner, such that a lesion forms substantiallybetween the first electrosurgical device and the second electrosurgicaldevice.

The steps of inserting and positioning electrosurgical device 400 mayoptionally be followed, for example prior to the commencement of thestep of delivering energy, by any number of steps, including, but notlimited to, one or more of: measuring one or more properties of a deviceor of tissue at or near the target treatment site; applying astimulation signal to a tissue (for example, neural tissue) at or nearthe target treatment site; measuring the reaction to stimulation (forexample, the somato-sensory evoked potential, or SSEP) of a tissue (forexample, muscular or neural tissue) in response to the application of astimulation signal at or near the target treatment site; inserting orremoving material at or near the target treatment site; and performinganother treatment procedure at or near the target treatment site.Further details regarding these steps may be found in U.S. patentapplication Ser. No. 11/105,527 (filed on Apr. 14, 2005), Ser. No.11/280,604 (filed on Nov. 15, 2005), Ser. No. 11/356,706 (filed on Feb.17, 2006), Ser. No. 11/381,783 (filed on May 5, 2006), and Ser. No.11/368,509 (filed on Mar. 7, 2006). Following the performance of one ormore of the above optional steps, electrosurgical device 400 may bereinserted, moved, or otherwise repositioned and any optional steps maythen be repeated.

In some embodiments, the step of delivering energy involves the creationof a lesion 404 at or adjacent to the superolateral aspect of thetransverse process, or alternatively, the creation of a lesion 704 atthe lamina of the vertebra. In any embodiments, as describedhereinabove, the lesion may be created substantially distal to an energydelivery portion of the energy delivery device. Such lesions may beeffective to alter a function of at least a portion of a medial branchof a dorsal ramus nerve. In some embodiments, the energy is delivered asradiofrequency electrical current having a frequency of between about 10kHz and about 1000 kHz, at a power of about 50 W, may be delivered tothe probe.

In embodiments of the present invention, the step of delivering energyto the tissue is preceded by, and/or performed at least partiallyconcurrently with, a step of cooling the energy delivery portion of theelectrosurgical device. As described hereinabove, in some embodiments,cooling may be achieved via the internal circulation of a fluid withinelectrosurgical device 400. In other embodiments, other means forcooling may be used, as described in U.S. patent application Ser. No.11/457,697, previously incorporated herein by reference. Cooling may beused to reduce the temperature of the tissue in the vicinity of the siteof energy delivery, allowing more energy to be delivered without causingan increase of temperature in surrounding tissue to an unsafe level. Thedelivery of more energy allows regions of tissue further away from theenergy delivery portion to reach a temperature at which a lesion canform, thus increasing the maximum size/volume of the lesion.Furthermore, depending on the structure of the electrosurgical device,cooling may allow for a lesion to form at a position that issubstantially distal to and, in some embodiments, spaced from the energydelivery portion. In some embodiments, again depending on the structureof the electrosurgical device, the lesion may from more in one directionthan in another direction. For example, the lesion may formsubstantially distal to the energy delivery portion or may formsubstantially in another direction, depending on the structure of theelectrosurgical device. Thus, cooling an electrosurgical probe maychange the size, shape, and location of formation of a lesion. Thelesion may be oblong or spherical in shape. In other embodiments thelesion may have a non-uniform shape.

In further embodiments, the step of cooling the electrosurgical devicemay be performed in a pulsed or intermittent manner. This may allow fora more accurate measurement of tissue temperature by a temperaturesensing device associated with the electrosurgical device. For example,in embodiments wherein the electrosurgical device is cooled via theinternal circulation of a cooling fluid delivered by a pump, the pumpmay be operated in a pulsed or intermittent manner. When the pump is‘on’, fluid will circulate within the electrosurgical device, and theelectrosurgical device and surrounding tissue will be cooled; when thepump is ‘off’, fluid will not circulate within the electrosurgicaldevice, and heat from the tissue in the vicinity of the electrosurgicaldevice may conduct back towards the electrosurgical device, causing theelectrosurgical device to heat to a temperature that is more indicativeof the temperature of the tissue in the vicinity of the electrosurgicaldevice. The temperature sensing device may sense this temperature, andmay thus give a more accurate reading of the temperature of the tissuein the vicinity of the electrosurgical device. When the pump returns tothe ‘on’ position, the electrosurgical device will again be cooled, andthe tissue adjacent the electrosurgical device will return to a coolertemperature. The pulsing of the pump may coincide with pulsing of energydelivered to the electrosurgical device, described further hereinbelow,such that cooling is only supplied to the electrosurgical device whileenergy is being delivered.

In some embodiments, the active cooling of the electrode may bemodulated during energy delivery (and in some cases, accompanied by amodulation of energy delivery), for example as follows: energy may bedelivered initially in conjunction with cooling of the electrode so thata lesion begins to form at some distance distally spaced apart from theelectrode; cooling may then be reduced, causing the lesion to extend atleast partially in the direction of the electrode. Thus, a furtherfeature of some embodiments of the present invention involves thecontrol of cooling parameters in order to create a lesion at a desiredlocation relative to the electrode. Further details regarding thisfeature are found in U.S. patent application Ser. No. 11/457,697,previously incorporated herein by reference. For example, an 18 AWGprobe having an exposed distal tip about 1.5 mm to about 2 mm in lengthand being cooled by a cooling fluid having a temperature of less than 30degrees Celsius at a rate of at least 10 mL/minute, will form a lesionabout 1.5 mm distal to the electrode tip. As the cooling is decreased,for example by lowering the fluid flow rate, the lesion will form closerto the probe tip. The parameters of cooling may be adjusted before,during or after energy delivery.

In some embodiments wherein the degree of cooling is modified during thecourse of a treatment procedure, the amount or degree of coolingsupplied to the electrosurgical device may be controlled actively by auser by modifying a flow-rate, or a temperature of the cooling fluid.For example, a temperature measured at the distal region of theelectrosurgical device may be displayed on a screen or other displaymeans. Based on this temperature, a user may desire to increase theamount of cooling supplied to the electrosurgical device, for example ifthe temperature is above a certain threshold level. The user may, insome embodiments, adjust the amount of cooling supplied by increasingthe flow-rate of cooling fluid. This may be accomplished by turning aknob on a pump, for example, or by opening a valve. In otherembodiments, the control of cooling may be passive and/or automatic. Forexample, a computer may automatically adjust a fluid flow-rate based ona temperature measured at the distal region of the electrosurgicaldevice. In another example, a fluid flow-rate may be fixed during thecourse of a treatment procedure, and may not be modified.

In some embodiments, after the creation of a lesion, electrosurgicaldevice 400 may be repositioned, and energy may again be delivered inorder to form one or more further lesions. For example, after theformation of a first lesion, the electrosurgical device 400 may bewithdrawn from the target site either partially or fully. In the case ofpartial withdrawal, energy may be delivered to the site at which theelectrosurgical device 400 has been withdrawn to, such that a secondlesion is formed. In the case of full withdrawal, electrosurgical device400 may be re-inserted and re-positioned at a second location, andenergy may be delivered to the second location to form a further lesion.The step of repositioning may be performed any number of times, to formany number of lesions, as determined by a user. In embodimentscomprising a steerable electrosurgical device, the electrosurgicaldevice may be repositioned without withdrawing the probe, by actuatingthe steering means associated with the probe.

In some embodiments, any or all of the method steps described above maybe performed with the aid of imaging. For example, the step of insertingelectrosurgical device 400 may be performed under X-ray fluoroscopicguidance. In a further embodiment, the imaging may be performed in agun-barrel manner, wherein the device is visualized along itslongitudinal axis.

In some embodiments, rather than being delivered in a continuous manner,energy may be delivered in a series of amplitude or frequency modulatedpulses, whereby tissue heating is inhibited by interrupting periods ofenergy delivery with periods in which energy is delivered at a lowervoltage. In one specific embodiment, energy is delivered according to aset duty cycle of signal on time/off time, wherein the signal is ‘on’less than 100% of the time, as follows: during signal ‘on time’ energyis delivered at a voltage that may beneficially be higher than voltagesthat can safely be used during continuous energy delivery (100% dutycycle) procedures; during signal ‘off time’, the heat generated in thevicinity of the probe may disperse throughout the tissue, raising thetemperature of tissue away from the probe, while tissue in the vicinityof the probe drops; energy is again applied and the delivery is cycledthrough ‘on time’ and ‘off time’ until a predetermined endpoint (e.g.time or temperature) is reached or until a practitioner decides to endthe treatment. The reduction in temperature of tissue in the vicinity ofthe electrode during signal ‘off time’ may allow a higher voltage to beused (during ‘on time’), than would tend to be used in a continuousenergy delivery procedure. In this way, the pulsing of energy delivery,either between signal ‘on time’ and ‘off time’, as described above, orbetween a higher voltage and a lower voltage (for example, a voltagecapable of generating a lesion in the tissue and a voltage not capableof generating a lesion in the tissue, given the frequency of energybeing delivered), the total amount of current deposited into the tissuemay be sufficient to create a larger lesion, at a further distance fromthe probe, than would be possible using continuous energy deliverywithout maintaining the tissue in the vicinity of the probe at atemperature that may cause charring. As mentioned hereinabove, thecreation of a larger lesion is beneficial as it would require relativelyless insertion and energy delivery steps in order to adequately treatthe tissue.

Depending, for example, on the configuration and positioning of theelectrosurgical device 400, as well as the degree of cooling supplied tothe electrosurgical device 400, the lesion formed at the target site 310may be of a variety of shapes and sizes. As described in U.S. patentapplication Ser. No. 11/457,697, previously incorporated herein byreference, lesion shape and location may be affected by the length ofthe energy delivery portion, for example an active electrode, of theelectrosurgical device. The shorter the active electrode, the moredistally, relative to the electrosurgical device, the lesion will form.In addition, the shape of the lesion will be generally more spherical ifless of the active electrode is exposed. For example, if the exposedlength of the distal end is limited substantially to the distal-mosthemisphere, i.e. the face, of the tip, then a substantially sphericallesion may form primarily distally with respect to the electrosurgicaldevice. Conversely, if more of the tip is exposed, then the lesion willappear more oblate and may form more radially (i.e. perpendicular to thelongitudinal axis of the electrosurgical device) around the distal endand the component of the lesion distal to the distal end will decrease.Thus, depending on the size and shape of the active electrode of theelectrosurgical device, the size and shape of the lesion may vary. Forexample, as shown in FIG. 4, in embodiments wherein the active electrode402 of electrosurgical device 400 extends proximally along the length ofthe probe for a small distance, for example between about 2 mm and about7 mm, and with a sufficient amount of cooling, for example between about10 ml/min and about 25 ml/min, lesion 404 may form around the conductiveportion as well as distal to the probe. Because lesions formed by thismethod may be substantially large, for example between about 100 mm³ andabout 1200 mm³ in volume, this method may be particularly useful forlesioning of the nerves of the medial branch of the dorsal ramus at thethoracic region of the spine. In some embodiments the lesion formed maybe greater than 1200 mm³.

In accordance with the methods outlined in the present disclosure, theelectrosurgical device or probe is positioned near the course of thetarget nerve. When energy is applied through the probe tip a lesionforms that blankets around the edges of the bone. In one embodiment thelesion is limited to the dorsal rami and the nerve root and the lateralbranch of the dorsal root remain unaffected. In the upper and lowersection of the thoracic spine from T1-T4 and T9-10, the medial branch ofthe dorsal ramus nerve crosses the superior-lateral portion of thetransverse process and the variability decreases near the bone. Hence asmaller tip size is sufficient to create an effective lesion. In oneembodiment as indicated in FIG. 12, the probe tip 1200 is about 3.5 mmand forms a lesion 1202 with a diameter of about 8 mm. The lesion 1202forms substantially distal to the probe tip 1200. The lesion may formbetween the probe tip 1200 and a segment of the thoracic vertebra. Inone example the segment of the thoracic vertebra is the transverseprocess. More specifically, the segment is the superior-lateral aspectof the transverse process. The distal projection 1204 of the lesion isabout 4 mm from the probe tip with a lesion volume of about 270 mm³. Thedistal projection is defined as the distance between the probe tip andthe distal edge of the lesion. In alternate embodiments the lesiondiameter can be about 6 mm to about 10 mm. In some embodiments thelesion diameter can be larger than 10 mm. In one example of embodimentof the present invention the electrosurgical device 900 is inserted atthe T4 vertebral level as indicated in FIG. 10. In another example thedevice 900 is inserted at the T10 vertebral level as shown in FIG. 11

In the mid thoracic region from T5-T9, there is a greater variability inthe path of the target nerve as the medial branch of the dorsal ramuscross through the intertransverse space. Hence, an electrosurgicaldevice with a larger tip size is required in order to effectively lesionthe target nerve. In one embodiment the probe tip 1300 is about 5 mm andlesion 1302 has a diameter of about 12 mm. The lesion 1300 formssubstantially distal to the probe tip 1300. The lesion may form betweenthe probe tip 1300 and a segment of the thoracic vertebra. In oneexample the segment of the thoracic vertebra is the transverse process.More specifically the segment is the superior-lateral aspect of thetransverse process. The distal projection 1304 is about 5 mm from theprobe tip with a lesion volume of about 900 mm³. In another example ofthe present embodiment the lesion size may vary from about 8 mm to about16 mm. In some embodiments the lesion size may be greater than 16 mm indiameter. In one example of embodiment of the present invention theelectrosurgical device 900 is inserted at the T6 vertebral level asshown in FIG. 11.

Thus, embodiments of the present invention allow for the treatment of athoracic region of a patient's body. Particularly, methods of thepresent invention may be used to create a lesion at a medial branch of athoracic dorsal ramus, for example in order to treat pain or otherpathologies involving the medial branch.

As described hereinabove, embodiments of a method of the presentinvention allow for the creation of a lesion between an energy deliveryportion of an electrosurgical device and some predetermined location,such as a segment of a thoracic vertebra. For example, a lesion may becreated substantially distal to the energy delivery portion bydelivering energy to the energy delivery portion and cooling the energydelivery portion. This provides an advantageous benefit not found in theprior art, in that it obviates the need for a probe to be placed in veryclose proximity to a target nerve in order to effectively lesion thetarget nerve

Some embodiments of the method comprise positioning an energy deliveryportion of an electrosurgical device to face a segment of a thoracicvertebra at a distance from the segment; and cooling the energy deliveryportion and delivering energy through the energy delivery portion. Insome embodiments a lesion is formed at least substantially distal to theenergy delivery portion. In some embodiments the lesion is formed at alocation at least between the energy delivery portion and the segment ofthe thoracic vertebra.

In some particular embodiments, the electrosurgical device may beinserted and positioned in a manner that is relatively safe, effective,and efficient. In addition, embodiments of the present invention allowfor the creation of a relatively larger lesion than previously possible,thereby reducing the amount of lesions that must be created in order tosufficiently treat the patient.

Embodiments of the invention described above are intended to beexemplary only. The scope of the invention is therefore intended to belimited solely by the scope of the appended claims.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the broad scope of theappended claims. All publications, patents and patent applicationsmentioned in this specification are herein incorporated in theirentirety by reference into the specification, to the same extent as ifeach individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

The invention claimed is:
 1. A method of treatment of a thoracic regionof a patient's body, the method comprising: inserting an introducerapparatus into the patient's body at an upstanding angle relative to ananterior-posterior axis of the patient's body in a cranial direction,the apparatus comprising a cannula and an obturator disposed within alumen of the cannula, the obturator protruding from a distal end of thecannula; positioning the apparatus such that a distal tip of theobturator abuts the superolateral aspect of the transverse process ofthe thoracic vertebra; removing the obturator from within the cannula;inserting an energy delivery portion of an electrosurgical device intothe cannula; positioning the energy delivery portion of theelectrosurgical device at the superolateral aspect of the transverseprocess of the thoracic vertebra at a distance from the superolateralaspect of the transverse process; and cooling the energy deliveryportion and delivering energy through the energy delivery portion to thesuperolateral aspect of the transverse process such that a lesion isformed at least distal to the energy delivery portion.
 2. The method ofclaim 1, wherein the cooling and the delivering energy cooperate to forma lesion at a location at least between the energy delivery portion andthe superolateral aspect of the transverse process of the thoracicvertebra.
 3. The method of claim 1, wherein the distance between theenergy delivery portion and the superolateral aspect of the transverseprocess of the thoracic vertebra is 0.5 mm to 4 mm.
 4. The method ofclaim 1, wherein the distance between the energy delivery portion andthe superolateral aspect of the transverse process of the thoracicvertebra is 2 mm.
 5. The method of claim 1, wherein the upstanding angleof the electrosurgical device comprises an angle of between 15° and 60°relative to an anterior-posterior axis of the patient's body in thecranial direction.
 6. The method of claim 1, wherein the upstandingangle of the electrosurgical device comprises an angle of 45° relativeto an anterior-posterior axis of the patient's body in the cranialdirection.
 7. The method of claim 1, wherein the upstanding angle of theelectrosurgical device comprises an angle of 15° relative to ananterior-posterior axis of the patient's body in the cranial direction.8. The method of claim 1, wherein the energy delivery portion ispositioned at a location in the region bounded by: a superior margin ofthe transverse process, an inferior margin of a superjacent transverseprocess, an anterior margin of the transverse process and an anteriormargin of the superjacent transverse process, a posterior margin of aspinous process of the thoracic vertebra, an inferior articular processof the thoracic vertebra and a superior articular process of asuperjacent thoracic vertebra, and a lateral margin of the transverseprocess and a lateral margin of the superjacent transverse process. 9.The method of claim 1, wherein the superolateral aspect of thetransverse process of the thoracic vertebra comprises a centroid regionof a transverse process.
 10. The method of claim 1, further comprisingpositioning the introducer apparatus within an intertransverse space,prior to inserting the electrosurgical device within the cannula. 11.The method of claim 10, the method further comprising: placing a depthstopper on the cannula adjacent to the surface of the patient's skin andpartially withdrawing the apparatus prior to moving the apparatus; andadvancing the apparatus until the depth stopper is adjacent to thepatient's skin, after moving the apparatus.
 12. The method of claim 1,wherein positioning the introducer apparatus within the intertransversespace comprises: moving the apparatus from the centroid region in acranial direction until the intertransverse space is reached.